Abstract: Expandable and contractible buoyancy modules are assembled to the risers of a deepwater exploration spar or other offshore structure to provide an upwardly directed buoyancy force to offset at least a portion of the weight of the riser. The buoyancy modules have a fabricated pressure tight expandable and contractible envelope composed of rubber or rubber-like material which is mounted onto a tubular member having a central passage for receiving the riser to be supported. The tubular member projects beyond the respective upper and lower ends of the envelope and defines upper and lower riser joint connectors and buoyancy module travel stops which secure the buoyancy module to the riser and provide for force transmission from the buoyancy module to selected locations along the length of the riser or to the upper end of the riser.

Abstract: A mudmat foundation for supporting an item of subsea equipment on the sea floor comprises a mudmat on which the item of subsea equipment may be supported and a plurality of legs which are pivotably connected to and depend downwardly from the mudmat. The legs are free to pivot outwardly relative to the mudmat upon insertion of the legs into the sea floor to thereby increase the load bearing capacity of the mudmat.

Abstract: A downhole safety valve for a central circulation completion system having concentric inner and outer tubular members defining a production bore therebetween comprises a generally cylindrical body which includes an outer surface which is sealed to the outer tubular member and an axial through bore to which the inner tubular member is secured. In this manner, the downhole safety valve forms a pressure barrier between a first portion of the production bore located below the body and a second portion of the production bore located above the body. The downhole safety valve further comprises at least one flow passage which extends through the body and communicates between the first and second portions of the production bore, and at least one closure member which is disposed across the flow passage to control fluid flow between the first and second portions of the production bore.

Abstract: A downhole safety valve for a central circulation completion system which comprises an inner tubular member that extends through an outer tubular member and a production bore which is defined between the inner and outer tubular members. The downhole safety valve comprises a generally cylindrical body which includes an outer surface and a through bore that extends generally axially through the body. The body is secured to the inner tubular member and is sealed to the outer tubular member to thereby form a pressure barrier between a first portion of the production bore located below the body and a second portion of the production bore located above the body. The downhole safety valve further comprises at least one flow passage which extends through the body and communicates between the first and second portions of the production bore, and at least one closure member which is disposed across the flow passage to control fluid flow between the first and second portions of the production bore.

Abstract: A wellhead system for petroleum producing wells comprises a “stack-down” casing hanger configuration. In this stack-down system, the hanger for each successively smaller diameter casing string is landed or “nested” within the hanger for the next larger casing string. This approach allows the pack-off for each casing hanger to be retrieved independently, thus allowing fluid communication to be established with any of the casing annuli after all of the casing strings and hangers have been installed. Thus the pressure in each annulus may be monitored while the well is in production mode.

Abstract: Expandable and contractible buoyancy modules are assembled to the risers of a deepwater exploration spar or other offshore structure to provide an upwardly directed buoyancy force to offset at least a portion of the weight of the riser. The buoyancy modules have a fabricated pressure tight expandable and contractible envelope composed of rubber or rubber-like material which is mounted onto a tubular member having a central passage for receiving the riser to be supported. The tubular member projects beyond the respective upper and lower ends of the envelope and defines upper and lower riser joint connectors and buoyancy module travel stops which secure the buoyancy module to the riser and provide for force transmission from the buoyancy module to selected locations along the length of the riser or to the upper end of the riser.

Abstract: A subsea pig launching apparatus for launching one or more pigs into a flowline which is fluidly connectable to a source of well fluid comprises at least one first hub to which the source of well fluid is connectable and which is in communication with the flowline, a first valve which is positioned between the first hub and the flowline, a second hub which is in communication with the flowline, and a pig launcher which is removably connectable to the second hub and which comprises at least one pig, at least one launch valve which is positioned between a pressure source and the pig, and a launch actuator for selectively opening and closing the launch valve. The launch actuator is controlled by a signal which is communicated through at least one of a number of external control and service lines that are connected to a control and service umbilical for the source of well fluid.

Abstract: A wellhead system for petroleum producing wells comprises a “stack-down” casing hanger configuration. In this stack-down system, the hanger for each successively smaller diameter casing string is landed or “nested” within the hanger for the next larger casing string. This approach allows the pack-off for each casing hanger to be retrieved independently, thus allowing fluid communication to be established with any of the casing annuli after all of the casing strings and hangers have been installed. Thus the pressure in each annulus may be monitored while the well is in production mode.

Abstract: A subsea pig launching apparatus for launching one or more pigs into a flowline which is fluidly connectable to a source of well fluid comprises at least one first hub to which the source of well fluid is connectable and which is in communication with the flowline, a first valve which is positioned between the first hub and the flowline, a second hub which is in communication with the flowline, and a pig launcher which is removably connectable to the second hub and which comprises at least one pig, at least one launch valve which is positioned between a pressure source and the pig, and a launch actuator for selectively opening and closing the launch valve. The launch actuator is controlled by a signal which is communicated through at least one of a number of external control and service lines that are connected to a control and service umbilical for the source of well fluid.

Abstract: A subsea system is provided for producing a number of subsea wells which may be arranged in groups. Each of the groups of subsea wellheads is connected to deliver production flow to a subsea manifold and each subsea manifold is connected to deliver production flow to a production riser. A plurality of production risers each being connected to receive production flow from one of said subsea manifolds extend from the subsea manifolds for groups of wells. A deep draft floating spar is located generally above the subsea wellheads with mooring lines and has a production platform located above the sea surface and has buoyancy and ballast chambers to control floatation. The spar structure defines a riser bore receiving the production risers extending from the subsea wellheads to the production platform. The spar is also capable of being shifted laterally by its mooring lines for positioning above a selected well to thus permit well intervention activities as needed.

Abstract: A subsea production system is provided for producing a number of subsea wells which may be arranged in groups. Each of the groups of subsea wellheads is connected to deliver production flow to a subsea manifold and each subsea manifold is connected to deliver production flow to a production riser. A plurality of production risers each being connected to receive production flow from one of said subsea manifolds extend from the subsea manifolds for groups of wells. A deep draft floating spar is located generally above the subsea wellheads with mooring lines and has a production platform located above the sea surface and has buoyancy and ballast chambers to control floatation. The spar structure defines a riser bore receiving the production risers extending from the subsea wellheads to the production platform. The spar is also capable of being shifted laterally by its mooring lines for positioning above a selected well to thus permit well intervention activities as needed.

Abstract: Flying lead hydraulic and electrical umbilical arrangements are disclosed for control of a subsea christmas tree for production and workover operations. Alternative arrangements for deep water ROV arrangements for a conventional christmas tree are illustrated in FIGS. 2A, 2B and in FIGS. 3A, 3B, and 3C. Alternative arrangements for a horizontal christmas tree are illustrated in FIGS. 5, 6, and 7.

Abstract: The present invention is directed to a valve position indicator for indicating an open or closed position of a valve having a valve stem, the valve position indicator comprising a body adapted to be mounted to a subsea xmas tree structure, a traveling block movably connected to the body by at least one guide bolt, the traveling block including a threaded hole for engaging a threaded extension shaft which is coupled to the valve stem, a rigid tube connected to the body and having first and second open ends, and a coiled spring member having one end connected to the traveling block and the other end extending through the first end of the rigid tube, wherein the extension of the spring member beyond the second end by a predetermined amount provides a visual indication that the valve is in its open or closed position, whereby movement of the traveling block in response to actuation of the valve will push or pull the spring member through the tube to provide the desired visual indication.

Abstract: A subsea wellhead tieback connector operatively used to connect to a marine riser pipe or a well conductor in a manner that that will not unthread or unloosen the joints of the riser pipe being unlocked. The tieback connector operates with a novel internal latching mechanism having a hydraulic piston, an inner body that stretches and deflects in a unique manner resulting in compression spring forces at two locations, an expanding lock ring, a threaded adjustment ring, and a reaction ring. During operation the tieback connector creates an enhanced mechanical advantage to originate a required pre-load force without the necessity of having to generate a large hydraulic force that would otherwise be needed.

Abstract: Apparatus and method for easily installing and effectively launching pipeline pigs into a subsea or other underwater pipeline accessible to a diver.

Abstract: A metal-to-metal sealing pipe swivel joint especially useful with a subsea well completion system to pivotally interconnect the subsea wellhead to a lay-away flowline, the swivel joint having an annular seal element with metallic sealing surfaces and inner and outer tubular elements, also with metallic sealing surfaces, that can be moved into or withdrawn from sealing engagement with the seal element sealing surfaces.